Control for hydraulic forward-reverse steering clutches

ABSTRACT

A control mechanism for a dual and selectable drive system, which system includes hydraulically actuated clutches to deliver driving power to either or both driving members whether the driving members are tracks or wheels. Such a drive system commonly known as a caterpillar drive. The control mechanism includes a pair of control arms arranged to actuate a pair of moveable pi

United States Patent Hagen et a1.

CONTROL FOR HYDRAULIC FORWARD-REVERSE STEERING CLUTCI-IES Donald H. Hagen; Donald L. Leopold, both of Hennepin County, Minn.

Inventors:

Related U.S. Application Data Continuation-in-part of Ser. No. 27,085, Apr. 9,

1970, abandoned.

U.S.C1 ..l92/51, 192/87.13, 192/109 F, l80/6.7 Int. Cl ..Fl6d 25/10 Field of Search ..180/6.7; 192/51,49, 87.11, 192/87.13, 109 F References Cited UNITED STATES PATENTS Sarver ..l92/l09 F Blydenburgh 192/49 X [151 3,643,769 Feb.22,1972

988,336 4/1965 Great Britain l 80/6.7

Primary ExaminerBenjamin W. Wyche Attorney-James R. Cwayna [5 7] ABSTRACT A control mechanism for a dual and selectable drive system, which system includes hydraulically actuated clutches to deliver driving power to either or both driving members whether the driving members are tracks or wheels. Such a drive system commonly known as a caterpillar drive. The control mechanism includes a pair of control arms arranged to actuate a pair of moveable piston elements, the piston elements being of the dual action and accumulator variety. The pistons are directly connected to the clutches for one directional hydraulic control and being connected through the accumulator for the other directional control, and further the arms being arranged through an over center mounting for locking engagement for the other directional control 2 Claims, 8 Drawing Figures PATENTEUFB22 I972 3. 643 769 SHEET 1 0F 3 FIG.1

INVENTOR.

DONALD H. HAGEN BY DONALD L. LEOPOLD ATTORNEY PAlENlEnriazzlmz SHEET 2 OF 3 I N VENTOR.

mm N0 w Y M ufwflm D T M M um mw PATENIEUFEB22|912 8,643,769

' sum 3 OF 3 INVIiNI'OR DONALD H. HAGEN BY DONALD L. LEOPOLD ATTORNY CONTROL FOR HYDRAULIC FORWARD-REVERSE STEERING CLUTCHES This is a continuation-in-part application of an application filed Apr. 9, 1970, Ser. No. 27,085, and now abandoned, which discloses the original subject matter of this application, this application disclosing additional subject matter within the scope of the original application.

The utilization of a caterpillar drive with steering clutches wherein the speeds of the driving member on the sides of the vehicle are controlled to obtain the directional control for the vehicle are well known in the art. Various means have been provided to afford the operator control of the clutches but most of these currently available units are cumbersome and not adaptable to relatively small vehicles nor do they provide the high degree of control which is desirable in and for small, fast moving vehicles such as all terrain vehicles, snowmobiles and the like.

Operators of such vehicles desire the touch control" to afford them a great degree of maneuverability but also desire rclicf from this constant driving strain when, for example, they are travelling over relatively open terrain where a minimum amount of control is necessary. This latter relief is possible with applicant's device as an accumulating device is provided to hold steering pressure when the control arms are shifted to an overcenter position.

With applicants improved device whereas in the initial disclosure of this concept a pair of pistons were necessary to perform the steering and accumulating pressure concept, with this new development the accumulator and the control piston are combined into a single element. This combination will substantially reduce the price of the unit and will provide a more thorough and positive acting unit in that all of the operations of this accumulator control member are common to a single element.

It is therefore an object of applicants invention to provide a steering control mechanism for what may be termed caterpillar drive and steerage devices which includes a hydraulic control system to control the driving clutches.

It is a further object of applicants invention to provide a steering control structure which includes a pair of independently operable steering arms controlling independent hydraulic clutch control cylinders.

It is a further object of applicants invention to provide a steering control structure which includes a pair of independently mounted hydraulic pistons mounted in conjunction with a pair of driving control arms which eliminates any complicated linkage therebetween and such that the entire control force may be directly delivered to the pistons without power loss therebetween.

It is still a further object of applicants invention to provide a hydraulic steering control mechanism having a pressure accumulating device therein permitting removal of control power while maintaining control.

It is still a further object of applicants invention to provide a steering control mechanism for a hydraulically controlled steering device which combines a pressure accumulating device and a steering actuating device into a common body member.

These and other objects and advantages of the invention will more fully appear from the following description made in connection with the accompanying drawings, wherein like reference characters refer to the same or similar parts throughout the several views, and in which:

FIG. I is a schematic illustration of a portion of a tracked vehicle illustrating the placement of the control system embodying applicants concepts;

FIG. 2 is an illustration of the selected actuating portion of FIG. I;

FIG. 3 is a longitudinally cross section taken substantially along line 33 of FIG. 2;

FIG. 4 is a section taken substantially along line 44 of FIG. 1 illustrating the control cylinders and their actuating handle connection;

FIG. 5 is a partial portion of FIG. 4 particularly illustrating the overcenter control arrangement between the control cylinder and an actuating handle and being drawn to an enlarged scale;

FIG. 6 is a longitudinal section taken through one of the control cylinders and its actuating handle; and,

FIG. 7 is a view similar to FIG. 2 illustrating a combined actuator accumulator construction embodying applicant's improvements; and,

FIG. 8 is a horizontal section taken substantially along line 88 of FIG. 7.

In accordance with the accompanying drawings applicant's control device is illustrated on a track driven vehicle and the controlled system includes a transmission I] which receives rotative power from an engine (not shown) and which delivers power to two independent track members 12 through a drive chain 13 or the like. To provide the caterpillar-type steering it is obvious that two tracks are provided and the transmission is capable of delivering power to both of the tracks and in this instance the power is available from both sides of the transmission, only one side being shown. Two hydraulic clutch systems are employed on either side of the transmission, one 15 being the clutch controlling forward drive and the other l6 controlling the rearward drive. It should be obvious that the rcla tive speeds of the independently driven tracks will provide the steering effect for the vehicle and this speed is controlled by the pressure exerted by the clutches as controlled through the hydraulic system employed herein. The entire hydraulic system is designated 20, and includes two operative handles 21, 22, controlling two independent and identical systems. One of the systems will be discussed at this time. Basically, the handle 21 controls a first hydraulic cylinder 23 through an operative rod 23a and the cylinder 23 is a two-way unit which, as illustrated in FIG. 6 provides a piston 24 such that hydraulic fluid may be forced from either the forward drive outlet 25 or the rear drive outlet 26. The rear drive outlet is connected directly to the rear drive clutch 16. The forward drive outlet 25 is connected to the forward drive clutch l5 and is also connected to an accumulator 27, which accumulator is pressure responsive and is particularly illustrated in FIG. 3. A reservoir unit for hydraulic fluid 28 communicates with cylinder 23 at the approximate center thereof through inlet 29 and this is the neutral position for the piston 24 of the cylinder 23. This reservoir unit 28 serves and is connected to both of the independent control cylinders.

More specifically, the control handles 21, 22 and their relation to the pistons and cylinders is illustrated in FIGS. 4,5, and 6.

A support plate 30 is provided and mounted to the frame of the vehicle to provide a mounting area for the handles 21 and 22 and the cylinders 23, 31. The cylinders 23, 31 are provided with a mounting flange 32, 33 having mounting apertures 32a, 33a therethrough to permit the same to rotatively mounted on the support 30 with pin members 34, 35, or the like. The cylinders themselves are illustrated in cross section in FIG. 6 and each includes a cylindrical body portion 36 having the closed, flanged end 37 and a rod receiving and sealing 38 to permit longitudinal and sealed movement of the piston 24 therewithin. Each of the cylinder bodies 36 provides a pair of outlets 25, 26, on the respective ends thereof, with as previously stated the outlet 25 being the forward drive outlet and the outlet 26 being the rear drive outlet. The reservoir inlet is located centrally of the body and is designated 29. In order to prevent wear of the O-ring on piston 24 the internal wall of the cylinder 36 is extended smoothly radially outwardly in the area directly aligned with the reservoir inlet as at 36a. One additional aperture is formed in the cylinder and this aperture is designated 40. This is simple bleed opening such that the system may be bled of air.

The piston rod 23 extends outwardly from the cylinder body 36 to a clevis 41 which is rotatably connected to a handle connecting link 42 which rotatable connection is obtained through aligned apertures through each of the elements with a pin member 43 providing thejoinder. Link 42 is provided with a spined aperture 44 which receives a reduced, spinked portion 45 of the handle 21 or handle 22. The handles are held thereon with a capture ring 45a.

A bearing and support member is designated 46 and is rigidly mounted in the support plate 30. This will, of course, support the handles in position for their proper operation.

An overcenter locking arrangement is afforded between the connecting links 42 and this arrangement is particularly illustrated in FIG. 5. As illustrated, an adjustable stop member 47 is provided which has opposed adjustment devices 48, 49, arranged thereon. As the handle 21 or 22 are rotated from the drivers position pushed forwardly the cylinder will rotate about its pinned end past center as illustrated by the center lines on FIG. where it will abut with the stop 48 and its overccnter location will not allow return unless a positive retractivc force is applied by the driver. This overcenter position will hold the elements in the position of FIG. 6 which is the forward drive position. It is in this overcenter position that the accumulator 27 comes into action.

As illustrated in FIG. 3 the accumulator includes a body 50 providing a chamber therein with a spring loaded piston 51 arranged for longitudinal movement therein. An adjustment screw 52 acts against a spring engaging member 53 which, in turn, controls and shifts a spring 54 and the piston Sll. An inlet-outlet communicates with the chamber and through a T- connection 56 with the forward drive hydraulic line. The purpose and action of the accumulator is to accumulate hydraulic fluid under pressure and to maintain this pressure when the handles are placed in the overcenter position. The piston 24 obviously creates a higher pressure in the hydraulic system as the same is moved towards the outlet end and the spring 54 of the accumulator will absorb this pressure and when the handle reaches the overcenter position the spring will maintain the hydraulic pressure in the system. Again, it should be obvious that the adjustment screw 52 will permit adjustment of the hydraulic pressure which will be exerted by the accumulator and the applicant has found that the accumulators should be balanced in accordance with the clutches and also to one another such that when both of the handles are moved to the overccntcr position the tracks will be driven at the same speed to drive the vehicle in a straight line.

In accordance with the improvement that forms the subject matter of this continuation-in-part application the actuator and accumulator device are in combined form. The single device is illustrated in F168. 7 and 8 and is generally designated 60.

In the form shown the combined unit includes a body member 61 providing an interior fluid containing cylinder 62, and having a control rod end 63 with a control rod packing gland member 64 or the like threadably received therein and sealed to permit the control rod 65 and its accompanying working piston 66 to function within the fluid cavity 62 of the body member 61. Obviously, this control rod member 65 is attached to the individual handle members for actuation and control of the fluid therein, for controlling the forward drive clutch mechanism and the rearward drive clutch mechanism 16. Obviously, two of these members 61 must be provided, one for each of the operating handles, and one for each of the corresponding track members of the vehicle. In the form shown a rear drive outlet member 67 is provided adjacent the end 63 of the body member such that fluid will be delivered thereto whenever the piston member 66 is moved rearwardly, or in the views shown to the right.

The reservoir attachment section 68 of course communicates with the reservoir 69 to maintain a supply of a fluid into the cavity 62 for providing the hydraulic fluid for control of the clutch mechanisms. The bleeder valve 70 again is provided on the body member 61 to properly bleed the hydraulic system.

The control for the forward drive clutch mechanism 15 is maintained through connection member 71 and obviously as the interior piston 66 is moved forwardly the fluid will be forced through the connector 71 and into the appropriate fluid line to drive the forward driving clutch mechanism 15.

As illustrated in the first form of the invention a groove 72 is provided adjacent to the reservoir inlet 68 and is arranged circumferentially about the interior of the cavity 62 and, as previously stated, this sort of groove will permit proper flow of the fluid into the interior of the member 61 for proper hydraulic flow thereto.

The combinative effect of this improvement is obtained by combining the aforementioned accumulator device with the control chamber, and, in the form shown, the body member 61 is extended as at 73 to provide means for mounting a spring loaded piston member 74 within the cavity 62 with a spring member 75 acting thereagainst to normally urge the piston 74 into a position where it will force fluid into the forward drive clutch control outlet 71. Arranged directly behind and actually aligned with the spring member is an adjustment member 76 which is fluidly sealed into the interior of the cavi ty 62 and an adjustment member such as the bolt 77 is arranged through a pin member 78 to abut with and move the spring tension adjustment member 76. In the form shown the pin member 78 would normally be received into the aforementioned apertures 32a, 33a, of the frame to permit oscillation of the cylinder body 61 as the handles 21, 22 of the unit are shifted. As illustrated, the adjustment member 77 is received through this pin member 78.

In operation of this particular unit it should be obvious that when the handles 21, 22 are shifted into their overccnter positions they will approximate the position of the piston 66 as illustrated in FIG. 8, and, at this point the handles 21, 22 being locked in their overcenter position, a constant pressure will be exerted against the fluid by the previously compressed piston member 74. This piston member 74 being urged forwardly by the spring member 75 will maintain the forward driving clutch control pressure. When the handles are drawn into reverse position this pressure will, of course, be substantially eliminated to the extent of the spring control mechanism and only the rearward motion of the handles 21, 22 will deliver fluid under pressure through the rearward drive connection 67 to the rearward clutch control 16. At this point the spring 75 will be uncompressed and there will be no fluid pressure on the forward drive clutch control.

Obviously, the pressure on the spring 75. and the aforementioned piston 74 will be controlled by operation of the control bolt '77 such that added clutch control driving pressure may be obtained simply by turning this member 77 inwardly to produce additional spring compression.

it'should be obvious that both of applicants concepts employ a unique fluid control pressure distributing unit with an accumulator device such that pressure will be maintained on the fluid system in at least one of the two operative conditions.

What we claim is:

1. A steering control mechanism for a vehicle having a pair of drive members and hydraulically actuated clutch mechanisms for selectively driving said drive members, said steering control including:

a. a pair of hydraulic cylinder and pistons arranged respectively to control said clutch members in both a forward and a rearward drive position;

b. means for actuating said pistons said actuating means in eluding a pair of rotatable handle members arranged and constructed to provide free movable control of said pistons through a first range of movement;

0. means for shifting said handles to a second overcenter locking position to lock the same in forward drive position; and,

d. pressure accumulating means receiving fluid from said cylinders when the same deliver fluid to the clutches to maintain pressure within the system.

2. The structure set forth in claim 1 and stop means controlling the overccntcr location of said handle members. 

1. A steering control mechanism for a vehicle having a pair of drive members and hydraulically actuated clutch mechanisms for selectively driving said drive members, said steering control including: a. a pair of hydraulic cylinder and pistons arranged respectively to control said clutch members in both a forward and a rearward drive position; b. means for actuating said pistons said actuating means including a pair of rotatable handle members arranged and constructed to provide free movable control of said pistons through a first range of movement; c. means for shifting said handles to a second overcenter locking position to lock the same in forward drive position; and, d. pressure accumulating means receiving fluid from said cylinders when the same deliver fluid to the clutches to maintain pressure within the system.
 2. The structure set forth in claim 1 and stop means controlling the overcenter location of said handle members. 